One of the most common times for a pregnancy to fail is in the first few weeks – often before the parent realises they are pregnant. This biologically fragile time has long remained a mystery for researchers as it involves the implantation of a tiny embryo in the womb, so it’s been pretty much impossible to observe the process.
Researchers from the University of Cambridge have been able to create embryos from mouse stem cells (rather than the usual way by combining an egg and sperm) in the lab, guiding their development to form a fully beating heart and the foundations of the entire brain – a first for this kind of study.
“This period is the foundation for everything else that follows in pregnancy. If it goes wrong, the pregnancy will fail,” say Professor Magdalena Zernicka-Goetz, who led the research published in Nature. “This period of human life is so mysterious, so to be able to see how it happens in a dish – to have access to these individual stem cells, to understand why so many pregnancies fail and how we might be able to prevent that from happening – is quite special.”
Formation and development of an embryo in the womb results in stem cells creating three different types of tissue structures: the embryonic tissue, the placenta and the yolk sac.
In the lab, the team combined cultured stem cells to represent the three main types of tissues, thereby creating an environment similar to the womb. They found that not only did extraembryonic tissues (those outside the embryo) communicate with embryonic tissues via chemical signalling, but also through touch. Through these communications, the embryo was able to successfully self-assemble and develop.
This communication between tissues is crucial for the embryo’s survival, explains Zernicka-Goetz. “We looked at the dialogue that has to happen between the different types of stem cell at the time – we’ve shown how it occurs and how it can go wrong.”
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This research is a step forward in stem cell science as the foundations for the whole brain were formed – the most progressed development of such embryonic tissue to date. “This opens new possibilities to study the mechanisms of neurodevelopment,” says Zernicka-Goetz.
The team is also excited about the prospects of using similar techniques on human models, which may help guide the development of “synthetic” organs (that is, organs manufactured, rather than developed in the usual way inside an animal’s body), bringing hope for humans waiting for transplants. For some time, advances in stem cell research have been hotly anticipated to have the potential to develop safe and effective treatments for a number of ailments.
“What makes our work so exciting is that the knowledge coming out of it could be used to grow correct synthetic human organs to save lives that are currently lost. It should also be possible to affect and heal adult organs by using the knowledge we have on how they are made.”